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Hypersensitive Sites
In genetics a hypersensitive site is a short region of chromatin and is detected by its super sensitivity to cleavage by DNase I and other various nucleases (DNase II and micrococcal nucleases). In a hypersensitive site, the nucleosomal structure is less compacted, increasing the availability of the DNA to binding by proteins, such as transcription factors and DNase I. These sites account for many inherited tendencies. Location Hypersensitive sites are found on every active gene, and many of these genes often have more than one hypersensitive site. Most often, hypersensitive sites are found only in chromatin of cells in which the associated gene is being expressed, and do not occur when the gene is inactive. In DNA being transcribed, 5'hypersensitive sites appear before transcription begins, and the DNA sequences within the hypersensitive sites are required for gene expression. Note: hypersensitive sites precede active promoters. Hypersensitive sites are generated as a result ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNAse Hypersensitive Site
Deoxyribonuclease (DNase, for short) refers to a group of glycoprotein endonucleases which are enzymes that catalyze the Hydrolysis, hydrolytic cleavage of Phosphodiester bonds, phosphodiester linkages in the DNA backbone, thus degrading DNA. The role of the DNase enzyme in cells includes breaking down extracellular DNA (ecDNA) excreted by apoptosis, necrosis, and neutrophil extracellular traps (NET) of cells to help reduce inflammatory responses that otherwise are elicited. A wide variety of deoxyribonucleases are known and fall into one of two families (Deoxyribonuclease I, DNase I or Deoxyribonuclease II, DNase II), which differ in their Substrate (biochemistry), substrate specificities, chemical mechanisms, and biological functions. Laboratory applications of DNase include Protein purification, purifying proteins when extracted from Prokaryote, prokaryotic organisms. Additionally, DNase has been applied as a treatment for diseases that are caused by ecDNA in the blood plasma. Assa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetics
Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar working in the 19th century in Brno, was the first to study genetics scientifically. Mendel studied "trait inheritance", patterns in the way traits are handed down from parents to offspring over time. He observed that organisms (pea plants) inherit traits by way of discrete "units of inheritance". This term, still used today, is a somewhat ambiguous definition of what is referred to as a gene. Trait inheritance and molecular inheritance mechanisms of genes are still primary principles of genetics in the 21st century, but modern genetics has expanded to study the function and behavior of genes. Gene structure and function, variation, and distribution are studied within the context of the cell, the organism (e.g. dominance), and within the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromatin
Chromatin is a complex of DNA and protein found in eukaryotic cells. The primary function is to package long DNA molecules into more compact, denser structures. This prevents the strands from becoming tangled and also plays important roles in reinforcing the DNA during cell division, preventing DNA damage, and regulating gene expression and DNA replication. During mitosis and meiosis, chromatin facilitates proper segregation of the chromosomes in anaphase; the characteristic shapes of chromosomes visible during this stage are the result of DNA being coiled into highly condensed chromatin. The primary protein components of chromatin are histones. An octamer of two sets of four histone cores (Histone H2A, Histone H2B, Histone H3, and Histone H4) bind to DNA and function as "anchors" around which the strands are wound.Maeshima, K., Ide, S., & Babokhov, M. (2019). Dynamic chromatin organization without the 30-nm fiber. ''Current opinion in cell biology, 58,'' 95–104. https://doi.o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNase I
Deoxyribonuclease I (usually called DNase I), is an endonuclease of the DNase family coded by the human gene DNASE1. DNase I is a nuclease that cleaves DNA preferentially at phosphodiester linkages adjacent to a pyrimidine nucleotide, yielding 5'-phosphate-terminated polynucleotides with a free hydroxyl group on position 3', on average producing tetranucleotides. It acts on single-stranded DNA, double-stranded DNA, and chromatin. In addition to its role as a waste-management endonuclease, it has been suggested to be one of the deoxyribonucleases responsible for DNA fragmentation during apoptosis. DNase I binds to the cytoskeletal protein actin. It binds actin monomers with very high (sub-nanomolar) affinity and actin polymers with lower affinity. The function of this interaction is unclear. However, since actin-bound DNase I is enzymatically inactive, the DNase-actin complex might be a storage form of DNase I that prevents damage of the genetic information. This protein is stor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclease
A nuclease (also archaically known as nucleodepolymerase or polynucleotidase) is an enzyme capable of cleaving the phosphodiester bonds between nucleotides of nucleic acids. Nucleases variously effect single and double stranded breaks in their target molecules. In living organisms, they are essential machinery for many aspects of DNA repair. Defects in certain nucleases can cause genetic instability or immunodeficiency. Nucleases are also extensively used in molecular cloning. There are two primary classifications based on the locus of activity. Exonucleases digest nucleic acids from the ends. Endonucleases act on regions in the ''middle'' of target molecules. They are further subcategorized as deoxyribonucleases and ribonucleases. The former acts on DNA, the latter on RNA. History In the late 1960s, scientists Stuart Linn and Werner Arber isolated examples of the two types of enzymes responsible for phage growth restriction in Escherichia coli ( E. coli) bacteria. One of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNase II
Deoxyribonuclease II (, ''DNase II'', ''pancreatic DNase II'', ''deoxyribonucleate 3'-nucleotidohydrolase'', ''pancreatic DNase II'', ''acid deoxyribonuclease'', ''acid DNase'') is an endonuclease that hydrolyzes phosphodiester linkages of deoxyribonucleotide in native and denatured DNA, yielding products with 3'-phosphates and 5'-hydroxyl ends, which occurs as a result of single-strand cleaving mechanism. As the name implies, it functions optimally at acid pH because it is commonly found in low pH environment of lysosomes. The action of DNase occurs in three phases. The initial phase introduces multiple nicks in the phosphodiester backbone. The second phase produces acid-soluble nucleotides. The third phase, which is the terminal phase, consists of hyperchromic shift resulting from reduction of oligonucleotides. There are several known DNases II, including: * DNase II alpha (usually known as DNase II), which is thought to be ubiquitously expressed in human tissue. It has bee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micrococcal Nuclease
Micrococcal nuclease (, ''S7 Nuclease'', ''MNase'', ''spleen endonuclease'', ''thermonuclease'', ''nuclease T'', ''micrococcal endonuclease'', ''nuclease T, ''staphylococcal nuclease'', ''spleen phosphodiesterase'', ''Staphylococcus aureus nuclease'', ''Staphylococcus aureus nuclease B'', ''ribonucleate (deoxynucleate) 3'-nucleotidohydrolase'') is an endo-exonuclease that preferentially digests single-stranded nucleic acids. The rate of cleavage is 30 times greater at the 5' side of A or T than at G or C and results in the production of mononucleotides and oligonucleotides with terminal 3'-phosphates. The enzyme is also active against double-stranded DNA and RNA and all sequences will be ultimately cleaved. Characteristics The enzyme has a molecular weight of 16.9kDa. The pH optimum is reported as 9.2. The enzyme activity is strictly dependent on Ca2+ and the pH optimum varies according to Ca2+ concentration. The enzyme is therefore easily inactivated by EGTA. Source ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcription Factor
In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. The function of TFs is to regulate—turn on and off—genes in order to make sure that they are expressed in the desired cells at the right time and in the right amount throughout the life of the cell and the organism. Groups of TFs function in a coordinated fashion to direct cell division, cell growth, and cell death throughout life; cell migration and organization (body plan) during embryonic development; and intermittently in response to signals from outside the cell, such as a hormone. There are up to 1600 TFs in the human genome. Transcription factors are members of the proteome as well as regulome. TFs work alone or with other proteins in a complex, by promoting (as an activator), or blocking (as a repressor) the recruitment of RNA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene Expression
Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product that enables it to produce end products, protein or non-coding RNA, and ultimately affect a phenotype, as the final effect. These products are often proteins, but in non-protein-coding genes such as transfer RNA (tRNA) and small nuclear RNA (snRNA), the product is a functional non-coding RNA. Gene expression is summarized in the central dogma of molecular biology first formulated by Francis Crick in 1958, further developed in his 1970 article, and expanded by the subsequent discoveries of reverse transcription and RNA replication. The process of gene expression is used by all known life—eukaryotes (including multicellular organisms), prokaryotes (bacteria and archaea), and utilized by viruses—to generate the macromolecular machinery for life. In genetics, gene expression is the most fundamental level at which the genotype gives rise to the phenotype, '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Promoter (genetics)
In genetics, a promoter is a sequence of DNA to which proteins bind to initiate transcription of a single RNA transcript from the DNA downstream of the promoter. The RNA transcript may encode a protein (mRNA), or can have a function in and of itself, such as tRNA or rRNA. Promoters are located near the transcription start sites of genes, upstream on the DNA (towards the 5' region of the sense strand). Promoters can be about 100–1000 base pairs long, the sequence of which is highly dependent on the gene and product of transcription, type or class of RNA polymerase recruited to the site, and species of organism. Promoters control gene expression in bacteria and eukaryotes. RNA polymerase must attach to DNA near a gene for transcription to occur. Promoter DNA sequences provide an enzyme binding site. The -10 sequence is TATAAT. -35 sequences are conserved on average, but not in most promoters. Artificial promoters with conserved -10 and -35 elements transcribe more slowly. All D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Histone Octamer
A histone octamer is the eight-protein complex found at the center of a nucleosome core particle. It consists of two copies of each of the four core histone proteins ( H2A, H2B, H3, and H4). The octamer assembles when a tetramer, containing two copies of H3 and two of H4, complexes with two H2A/H2B dimers. Each histone has both an N-terminal tail and a C-terminal histone-fold. Each of these key components interacts with DNA in its own way through a series of weak interactions, including hydrogen bonds and salt bridges. These interactions keep the DNA and the histone octamer loosely associated, and ultimately allow the two to re-position or to separate entirely. History of research Histone post-translational modifications were first identified and listed as having a potential regulatory role on the synthesis of RNA in 1964. Since then, over several decades, chromatin theory has evolved. Chromatin subunit models as well as the notion of the nucleosome were established in 197 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deoxyribonuclease
Deoxyribonuclease (DNase, for short) refers to a group of glycoprotein endonucleases which are enzymes that catalyze the hydrolytic cleavage of phosphodiester linkages in the DNA backbone, thus degrading DNA. The role of the DNase enzyme in cells includes breaking down extracellular DNA (ecDNA) excreted by apoptosis, necrosis, and neutrophil extracellular traps (NET) of cells to help reduce inflammatory responses that otherwise are elicited. A wide variety of deoxyribonucleases are known and fall into one of two families (DNase I or DNase II), which differ in their substrate specificities, chemical mechanisms, and biological functions. Laboratory applications of DNase include purifying proteins when extracted from prokaryotic organisms. Additionally, DNase has been applied as a treatment for diseases that are caused by ecDNA in the blood plasma. Assays of DNase are emerging in the research field as well. Types The two main types of DNase found in metazoans are known as deoxyr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
